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    Abietic acid

    Main component of the coniferous resin used as soldering flux. C20 H30 O2, molecular weight 302, melting point 174-175°C. Insoluble in water, but soluble in chloroform and alcohol. At room temperature it is inactive against metals; however, beyond the melting point, it reacts with CuO, SnO, PbO and similar to metal salts and water.

    CuO + 2 C19 H29 COOH → Cu(C 19 H 29 COO)2 + H2 O

    The reaction occurring here turns carboxylic acid back into abietic acid and increases the capacity of the solder joint.